U.S. patent number 6,198,494 [Application Number 09/039,897] was granted by the patent office on 2001-03-06 for image recording apparatus with plural print heads.
This patent grant is currently assigned to Konica Corporation. Invention is credited to Takashi Deguchi, Tsuyoshi Haraguchi, Tuyosi Hattori, Takashi Igarashi.
United States Patent |
6,198,494 |
Haraguchi , et al. |
March 6, 2001 |
Image recording apparatus with plural print heads
Abstract
In a color image recording apparatus provided with plural print
heads and a conveyor, each print head includes a plurality of
recording elements aligned along at least a single line in a
primary scanning direction and the plural print heads are arranged
in parallel to each other in the primary scanning direction so that
plural component images of the color image are formed parallel
respectively by the plural print heads. A reference component image
forming device controls the plural pieces of print heads so as to
form and superimpose plural reference component images based on the
reference component image data and timing setting values. A timing
correcting unit analyzes positional deviations in the secondary
scanning direction among the plural superimposed reference
component images and corrects the timing setting values on the
basis of the positional deviations in the secondary scanning
direction.
Inventors: |
Haraguchi; Tsuyoshi (Tokyo,
JP), Deguchi; Takashi (Tokyo, JP), Hattori;
Tuyosi (Tokyo, JP), Igarashi; Takashi (Tokyo,
JP) |
Assignee: |
Konica Corporation (Tokyo,
JP)
|
Family
ID: |
13299224 |
Appl.
No.: |
09/039,897 |
Filed: |
March 16, 1998 |
Foreign Application Priority Data
|
|
|
|
|
Mar 19, 1997 [JP] |
|
|
9-065861 |
|
Current U.S.
Class: |
347/232; 347/237;
358/302 |
Current CPC
Class: |
H04N
1/506 (20130101); B41J 2/47 (20130101) |
Current International
Class: |
H04N
1/50 (20060101); B41C 001/04 () |
Field of
Search: |
;347/116-118,129,130,19,232,234,237 ;358/1.2,1.4,1.8,1.9,302
;395/102,104,108,109 ;355/32,37 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pendegrass; Joan
Attorney, Agent or Firm: Frishauf, Holtz, Goodman, Langer
& Chick, P.C.
Claims
What is claimed is:
1. An apparatus for recording a color image on a recording medium
by relatively scanning the recording medium in a primary scanning
direction and in a secondary scanning direction substantially
perpendicular to the primary scanning direction, said apparatus
comprising:
plural print heads arranged in parallel to each other in the
secondary scanning direction, each said print head comprising a
plurality of recording elements aligned along at least a single
line in the primary scanning direction;
conveying means for conveying the recording medium relatively to
the plural print heads in the secondary scanning direction;
control means for controlling each of the plural print heads to
record a line image in the primary scanning direction on the
recording medium so as to form plural component line images of the
color image while the recording medium is conveyed in the secondary
scanning direction, and for controlling image forming timing for
each print head based on a timing setting value of each print head
so as to superimpose the plural component line images on the
conveyed recording medium;
reference component image forming means for controlling the plural
print heads to form and superimpose plural reference component
images on the conveyed recording medium based on reference
component image data and the timing setting value of each print
head;
timing correcting means for analyzing positional deviations in the
secondary scanning direction among the plural superimposed
reference component images, and correcting the timing setting value
of each print head based on the positional deviations in the
secondary scanning direction;
wherein the reference component image forming means determines an
arrangement between image data and the plurality of recording
elements in the primary scanning direction based on arrangement
setting data; and
arrangement correcting means for analyzing arrangement deviations
in the arrangement between the image data and the plurality of
recording elements in the primary scanning direction among the
plural print heads from the plural superimposed reference component
images, and correcting the arrangement setting data based on the
arrangement deviations.
2. The apparatus of claim 1, wherein the plurality of recording
elements of each print head are divided into plural blocks and the
timing setting value of each print head is determined with respect
to each block of each print head.
3. The apparatus of claim 1, wherein the timing setting value of
each print head is determined with respect to each recording
element of each print head.
4. The apparatus of claim 1, wherein the arrangement setting data
is corrected so as to allow each print head to have a standard
image resolution.
5. The apparatus of claim 4, wherein the plural print heads
comprise an LED print head and a vacuum fluorescent print head, and
an image resolution of the vacuum fluorescent print head is used as
the standard image resolution.
6. The apparatus of claim 4, wherein when an image resolution of
each print head is higher than the standard image resolution, the
image data is enlarged in the primary scanning direction so as to
enlarge a length of the line images, and when the image resolution
of each print head is lower than the standard image resolution, the
image data is reduced in the primary scanning direction so as to
reduce the length of the line images.
7. The apparatus of claim 6, wherein when the image data is
enlarged in the primary scanning direction, a number of the image
data to be added is adjusted, and when the image data are reduced
in the primary scanning direction, a number of the image data to be
eliminated is adjusted.
8. The apparatus of claim 7, wherein positions of the image data to
be eliminated are made different for each primary scanning
line.
9. The apparatus of claim 6, wherein the arrangement setting data
is set so as to one of: (i) enlarge a ratio of the length of the
line images to a number of the image data when the image data is
corrected so as to enlarge the length of the line images in the
primary direction, and (ii) reduce the ratio when the image data is
corrected so as to reduce the length of the line images in the
primary direction.
10. The apparatus of claim 1, wherein one of the plural print heads
is used as a reference print head, and the arrangement setting data
of another one of the plural print heads is corrected such that an
image resolution of another one of the plural print heads is made
to conform with an image resolution of the reference print
head.
11. The apparatus of claim 10, wherein the plural print heads are
adapted to be replaceable.
12. The apparatus of claim 10, wherein all of the plural print
heads except the reference print head are adapted to be
replaceable.
13. The apparatus of claim 1, wherein the reference component image
data is stored in a memory in the apparatus.
14. The apparatus of claim 1, wherein the reference component image
forming means is incorporated in a body of the apparatus.
15. The apparatus of claim 1, wherein the plural heads are
integrated in a single body.
16. The apparatus of claim 1, wherein the arrangement correcting
means corrects the arrangement setting data based on one of the
plural print heads for only another one of the plural print
heads.
17. The apparatus of claim 1, wherein each print head conducts
exposure recording with a different wavelength light.
18. The apparatus of claim 17, wherein the plural print heads
comprise print heads for blue light recording, green light
recording and red light recording.
19. The apparatus of claim 1, wherein the arrangement setting data
includes a first arrangement setting value for adjusting a
recording deviation between respective ones of the print heads, and
a second arrangement setting value for adjusting a recording
position of the color image on the recording medium, and wherein
the arrangement correcting means corrects the first arrangement
setting value and the second arrangement setting value based on the
plural superimposed reference component images.
20. An apparatus for recording a color image on a recording medium
by relatively scanning the recording medium in a primary scanning
direction and in a secondary scanning direction substantially
perpendicular to the primary scanning direction, said apparatus
comprising:
plural print heads arranged in parallel to each other in the
secondary scanning direction, each said print head comprising a
plurality of recording elements aligned along at least a single
line in the primary scanning direction;
conveying means for conveying the recording medium relatively to
the plural print heads in the secondary scanning direction;
control means for controlling each of the plural print heads to
record a line image in the primary scanning direction on the
recording medium so as to form plural component line images of the
color image while the recording medium is conveyed in the secondary
scanning direction, and for controlling image forming timing for
each print head based on a timing setting value of each print head
so as to superimpose the plural component line images on the
conveyed recording medium;
reference component image forming means for controlling the plural
print heads to form and superimpose plural reference component
images on the conveyed recording medium based on reference
component image data and the timing setting value of each print
head;
timing correcting means for analyzing Positional deviations in the
secondary scanning direction among the plural superimposed
reference component images, and correcting the timing setting value
of each print head based on the positional deviations in the
secondary scanning direction; and
a recording medium holding section which holds the recording medium
during recording, and wherein the plural print heads and the
recording medium holding section are arranged so as to be
relatively shiftable in a direction different from the secondary
scanning direction.
21. An apparatus for recording a color image on a recording medium
by relatively scanning the recording medium in a primary scanning
direction and in a secondary scanning direction substantially
perpendicular to the primary scanning direction, said apparatus
comprising:
plural print heads arranged in parallel to each other in the
secondary scanning direction, each said print head comprising a
plurality of recording elements aligned along at least a single
line in the primary scanning direction;
conveying means for conveying the recording medium relatively to
the plural print heads in the secondary scanning direction;
control means for controlling each of the plural print heads to
record a line image in the primary scanning direction on the
recording medium so as to form plural component line images of the
color image while the recording medium is conveyed in the secondary
scanning direction, and for controlling image forming timing for
each print head based on a timing setting value of each print head
so as to superimpose the plural component line images on the
conveyed recording medium;
reference component image forming means for controlling the plural
print heads to form and superimpose plural reference component
images on the conveyed recording medium based on reference
component image data and the timing setting value of each print
head; and
timing correcting means for analyzing positional deviations in the
secondary scanning direction among the plural superimposed
reference component images, and correcting the timing setting value
of each print head based on the positional deviations in the
secondary scanning direction; and
wherein the timing setting value of each print head includes a
first timing setting value for adjusting a recording deviation
between each print head and another print head, and a second timing
setting value for adjusting a recording position of the color image
on the recording medium, and wherein the timing correcting means
corrects the first timing setting value and the second timing
setting value based on the plural superimposed reference component
images.
22. The apparatus of claim 21, wherein the plurality of recording
elements of each print head are divided into plural blocks and the
timing setting value of each print head is determined with respect
to each bock of each print head.
23. The apparatus of claim 21, wherein the timing setting value of
each print head is determined with respect to each recording
element of each print head.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an image recording apparatus in
which recording is conducted by a plurality of paralleled print
heads in each of which a plurality of light emitting elements are
linearly aligned in the primary scanning direction.
Conventionally, as an apparatus in which an image is recorded with
plural-time exposure for each pixel by the use of a print head
equipped with an array-shaped light source in which light emitting
elements are linearly aligned in a direction (the primary scanning
direction) perpendicular to the conveying direction (the secondary
scanning direction) of the photosensitive material used as an image
recording medium, an apparatus provided with a LED array, a vacuum
fluorescent indicating tube or a liquid crystal shutter array is
known.
Further, as an apparatus in which recording is conducted by a
non-exposure system such as a melting heat transfer system or a
sublimating heat transfer system, a color image recording apparatus
provided with a thermal print head in which heat generating
elements are aligned in an array form is known.
Also, a color image recording apparatus using three print heads
provided with three kinds of light emitting elements different in
the wavelength of emitted light such as red, green and blue is
known. In the color image recording apparatus, each of the three
print head records an image one by one on the same line of pixels
in order to obtain a color image. Further, in order to increase the
recording speed, a method of using a plurality of the same kind of
print head is known.
Incidentally, in the image recording apparatus provided with a
plurality of print heads, it may be difficult to perfectly conform
the actual image resolution of each print head to others. Even if
the same kind of print heads are provided with the same image
resolution, the distances among pixels in the primary scanning
direction may become different among the print heads due to
manufacturing errors of the print heads.
As a result, since the positions of the recorded image (pixel) in
the primary scanning direction become different among the print
heads, for example, color blur may take place on the edge portion
of an image in the case that the image is recorded with
multi-colors. As the worst case, color deviation in which the
positions of images are deviated for each color may occur,
resulting in that image quality may be degraded greatly.
Now, the color blur and the color deviation are explained more with
reference to FIG. 11. In FIG. 11, the positions of print heads are
adjusted such that color blur and color deviation do not take place
at the position of address 0, thereafter exposure recording is
conducted in the primary scanning direction with a given pixel
interval by the print heads. At the position of address 767 in the
vicinity of the center of the scanning line, color blur and color
deviation take place, and at the position of address 2559
corresponding to the right edge, the positions of the recorded
pixels are completely deviated from each other.
In a print head such as a vacuum fluorescent indicating tube in
which a mask pattern of elements of a line is produced with the use
of photo resist, errors in image resolution are small. In contrast,
with a long print head in which a plurality of blocks each composed
of 128 pieces of light emitting elements such as LED are combined,
the above image degradation noticeably take place.
Further, in the case that an exposure section is constructed by a
combination of different types of print heads such as a LED print
head and a vacuum fluorescent print head, even if the different
types of print heads are indicated with the same size such as 300
dpi (dot/inch), there may be errors in image resolution smaller
than 1.0%. Color blur and color deviation may be caused by the
errors smaller than 1.0% to an easily noticeable extent depending
on the size of image.
Further, even in a monochromatic image, in order to reduce density
irregularities by averaging dispersion in luminance among light
emitting elements, or in order to make the life of a print head
longer by reducing the light emission amount per a single print
head, plural pieces of print heads are used so as to form an image
with superimposed pixels. In this case, color blur and color
deviation may be caused by deviation in the recorded positions of
the superimposed pixels.
The deviation in the recording positions in the primary scanning
direction is stated above. Also, the deviation in the recording
positions in the secondary scanning direction is a problem as same
as in the primary scanning direction. As a popular case as the
deviation in the recording positions in the secondary scanning
direction, the deviation may be caused in the case that the
recording timing in the secondary scanning direction is not
appropriately set for the relationship between the conveying speed
of an image recording medium and the distance between print heads.
In addition, in the case that the degree of parallelism between
print heads is not satisfied with a predetermined level, or in the
case that the print head is warped or curved, the deviations in the
recording position in the secondary scanning direction are varied
depending on the position in the primary scanning direction. Also,
when the position of the first recording element on each print head
is not parallel to the secondary scanning direction, color
deviation, namely color deviation in the primary scanning
direction, may occur.
In addition, depending upon the accuracy of the conveyance speed of
the image recording medium, or the accuracy of the conveyance
position in the primary scanning direction, an image may not be
recorded at a desired position on the recording medium. In the case
of prints with margins, prints having different margin amounts
between laterally and longitudinally may occur. In addition, when a
borderless print (which is a common print format in a silver halide
print), it was problematic that unnecessary margins occur. Although
it may be possible to increase the degree of precision in
manufacturing and assembling so as to minimize the deviation in the
recording positions in the primary scanning direction and in the
secondary scanning direction as small as possible, increasing the
degree of precision of machinery parts and lowering in assembling
efficiency may raise the manufacturing cost. Further, even if the
deviation in the recording positions is adjusted as small as
possible at the time of shipment, it may be difficult to avoid
deviations in recording position taking place due to the following
causes: working environment such as temperature and humidity,
deterioration due to transportation or long term usage, fluctuation
due to wear or friction force down in driving system in the
secondary direction, physical property change due to material
change of a recording medium, position change due to assembling or
disassembling at the time of print head replacement or at the time
of removing the jammed recording medium.
SUMMARY OF THE INVENTION
In view of the above problems, the objective of the present
invention is to provide an image recording apparatus with the
structure capable of eliminating deviations in recording positions
by the apparatus itself when an image is recorded by a plural
pieces of recording heads, whereby high quality image can be
secured for long term.
The above objective can be attained by either one of structures
described in the following items.
Item 1. In an image recording apparatus comprising:
a recording section in which plural pieces of print heads in each
of which recording elements to record image data on an image
recording medium are linearly aligned in plural lines are arranged
in parallel to each other in the relative conveying direction of an
image recording medium;
control means to control the output toward the recording section on
the basis of image data; and
conveying means to convey the image recording medium in
relationship to the print heads;
the apparatus is characterized by comprising correction means to
correct the image data in accordance with the difference between
the standard image resolution and the image resolution of the print
heads.
With the structure described in Item 1, by correcting the image
data on the basis of the difference between the standard image
resolution and the image resolution of the print heads, the
apparent image resolution of each print head is conformed with the
target image resolution, thereby reducing color blur in the
recorded image and avoiding color deviation, deterioration in
sharpness, and image-doubling. As a result, high grade visual image
can be obtained.
Item 2. When the image resolution of the print head is higher than
the standard image resolution, the image data is corrected so as to
be enlarged in the aligning direction of the recording elements,
while when the image resolution of the print head is lower than the
standard image resolution, the image data is corrected so as to be
reduces in the aligning direction of the recording elements.
With the structure described in Item 2, the image data is subject
to enlarging or reducing process so as to conform the image
resolution of the print head with that of the standard image
resolution.
Item 3. One of the print heads in the recording section is the
standard print head and the correction means corrects image data
for the other print heads.
With the structure described in Item 3, since the correction for
the image data is conducted based the difference between the image
resolution of the standard print head and the image resolution of
the other print heads, the positions of pixels being recorded are
registered with a simple manner without measuring a true image
resolution of each print head. Further, since the correction is
conducted for the print heads other than the standard print head,
the correction work for a single piece of the print head can be
reduced in comparison with the correction to conform absolutely
image resolutions with the standard one.
Item 4. The recording section is constructed by arranging a print
head using LED and a vacuum fluorescent indicating tube are by
plural pieces in parallel in the relative conveying direction of
the image recording medium and the correction means uses the image
resolution of the vacuum fluorescent indicating tube as the
standard image resolution.
With the structure described in Item 4, by using the image
resolution of the vacuum fluorescent indicating tube as the
standard image resolution, errors in the image resolution can be
refrained from occurring as far as possible and the image
resolution can be conformed with the target image resolution.
Item 5. The print head is divided into several blocks in the
aligned direction of the recording elements and the correction
means corrects the image data in accordance with the difference
between the image resolution of each block and the standard image
resolution.
With the structure described in Item 5, since the deviation in
distance between neighboring pixels at joint section of the
recording element blocks is corrected for each recording element
block, the positions of pixels being recorded are registered more
precisely, thereby enhancing the correction effect.
Item 6. The correction means enlarges the image data in the
aligning direction by adding specific pixels and reduces it by
eliminating specific pixels.
With the structure described in Item 6, since the enlarging or
reducing process for the image data is conducted by adding or
eliminating pixels, the correction process for the image data can
be conducted by a simple calculation without adding a new hard
ware.
Item 7. In the elimination of the pixels, the position of the
eliminated pixels are set to be different for each line of the
image data in the aligning direction of the recording elements.
With the structure described in Item 7, since an event that pixels
are eliminated at the same position can be avoided, the extent that
image pattern is lost can be minimized, thereby refraining image
quality from deteriorating.
Item 8. The apparatus is provided with image resolution measuring
means to measure the image resolution of the print head.
With the structure described in Item 8, since the image resolution
is measured with the image resolution measuring means, the
correcting process can be conducted automatically without hands.
For example, the position of the print head can be readjusted when
the assembling machinery precision is changed due to heat change
with time elapse or vibration.
Item 9. An image recording apparatus comprising:
a recording section in which plural pieces of print heads in each
of which a plurality of recording elements to record image data on
an image recording medium are aligned in the primary scanning
direction are arranged in parallel to each other;
recording control means for controlling the recording section to
conduct recording while the recording region of each print head is
shifted in the secondary scanning direction relatively for the
image recording medium so as to be superimposed on that of other
print heads;
recording timing control means for controlling the recording timing
of each print head in the secondary scanning direction based on set
values;
recording timing setting value correcting means for correcting
variably the setting values of the recording timing of at least one
print head; and
standard image forming means for forming a standard image on the
image recording medium based on standard image forming data,
wherein the recording position information of each print head in
the secondary scanning direction is readable from the standard
image; wherein the setting values of the recording timing are
corrected so as to correct deviations in recording position of each
print head on the image recording medium in the secondary scanning
direction on the basis of the formed standard image.
With the structure described in Item 9, the recording position
information of each print head in the secondary scanning direction
is read from the standard image formed based on the standard image
forming data, and the timing setting values of each print head in
the secondary scanning direction are corrected among the print
heads based on the recording position information, whereby
deviations in recording position of each print head on the
recording medium in the secondary scanning direction can be
corrected so that image quality can be improved.
Item 10. An image recording apparatus comprising:
a recording section in which plural pieces of print heads in each
of which a plurality of recording elements to record image data on
an image recording medium are aligned in the primary scanning
direction are arranged in parallel to each other;
recording control means for controlling the recording section to
conduct recording while the recording region of each print head is
shifted in the secondary scanning direction relatively for the
image recording medium so as to be superimposed on that of other
print heads;
data-element relationship control means for correcting the
relationship between the image data and the corresponding recording
elements in the primary direction of the print head based on
setting values;
data-element relationship setting value correcting means for
correcting variably the setting values of the data-element
relationship of at least one print head; and
standard image forming means for forming a standard image on the
image recording medium based on standard image forming data,
wherein the recording position information of each print head in
the primary scanning direction is readable from the standard
image;
wherein the setting values of the data-element relationship are
corrected so as to correct deviations in recording position of each
print head on the image recording medium in the primary scanning
direction on the basis of the formed standard image.
With the structure described in Item 10, the recording position
information of each print head in the primary scanning direction is
read from the standard image formed based on the standard image
forming data, and the setting values of each print head to
determine the relationship between the image data and the
corresponding recording element in the primary scanning direction
are corrected among the print heads based on the recording position
information, whereby deviations in recording position of each print
head on the recording medium in the primary scanning direction can
be corrected so that image quality can be improved.
Item 11. An image recording apparatus comprising:
a recording section in which plural pieces of print heads in each
of which a plurality of recording elements to record image data on
an image recording medium are aligned in the primary scanning
direction are arranged in parallel to each other;
recording control means for controlling the recording section to
conduct recording while the recording region of each print head is
shifted in the secondary scanning direction relatively for the
image recording medium so as to be superimposed on that of other
print heads;
recording timing control means for controlling the recording timing
of each print head in the secondary scanning direction based on set
values;
recording timing setting value correcting means for correcting
variably the setting values of the recording timing of at least one
print head; and
first standard image forming means for forming a first standard
image on the image recording medium based on standard image forming
data, wherein the recording position information of each print head
in the secondary scanning direction is readable from the first
standard image;
data-element relationship control means for correcting the
relationship between the image data and the corresponding recording
elements in the primary direction of the print head based on
setting values;
data-element relationship setting value correcting means for
correcting variably the setting values of the data-element
relationship of at least one print head; and
second standard image forming means for forming a second standard
image on the image recording medium based on standard image forming
data, wherein the recording position information of each print head
in the primary scanning direction is readable from the second
standard image;
wherein the setting values of the recording timing are corrected so
as to correct deviations in recording position of each print head
on the image recording medium in the secondary scanning direction
on the basis of the formed first standard image, and the setting
values of the data-element relationship are corrected so as to
correct deviations in recording position of each print head on the
image recording medium in the primary scanning direction on the
basis of the formed second standard image.
With the structure described in Item 11, the recording position
information of each print head in the secondary scanning direction
is read from the first standard image formed based on the first
standard image forming data, and the timing setting values of each
print head in the secondary scanning direction are corrected among
the print heads based on the recording position information,
whereby deviations in recording position of each print head on the
recording medium in the secondary scanning direction can be
corrected, further the recording position information of each print
head in the primary scanning direction is read from the second
standard image formed based on the second standard image forming
data, and the setting values of each print head to determine the
relationship between the image data and the corresponding recording
element in the primary scanning direction are corrected among the
print heads based on the recording position information, whereby
deviations in recording position of each print head on the
recording medium in the primary scanning direction can be
corrected, whereby image quality can be improved.
Item 12. The recording timing setting value correcting means
corrects variably setting value independently for each element or
for each of plural divided groups of recording elements for the
print head whose recording timing setting values are
changeable.
With the structure described in Item 12, even when a relative
positional relationship among the print heads is not parallel to
each other or even when the print head can not maintain its
straightness and warp or curve takes place, the deviations in
recording position can be reduced.
Item 13. The data-element relationship setting values are so
corrected that each print head has a standard image resolution.
With the structure described in Item. 13, since the image
resolution of each print head conforms with the standard image
resolution, the deviations in recording position in the primary
scanning direction among the print heads can be reduced, thereby
reducing color blur in the recorded image and avoiding color
deviation, deterioration in sharpness, and image-doubling. As a
result, high grade visual image can be obtained.
Item 14. The standard image resolution is the image resolution of
the standard print head which is either one of the plural pieces of
print heads in the recording section and the data-element
relationship setting values of the print heads other than the
standard print head are corrected variably.
With the structure described in Item. 14, he image data is subject
to enlarging or reducing process so as to conform the image
resolution of the print head with that of the standard image
resolution.
Item 15. The plural pieces of print heads comprises a LED print
head and a vacuum fluorescent print head.
With the structure described in Item. 15, in the case that, for
example, three colors of R, G, B print heads are used, the print
heads can be appropriately selectively used such that the LED print
head is used as the R print head, and the vacuum fluorescent print
head which has relatively high luminance and high response and can
divide colors easily with color filters is used as the G print head
and the B print head.
Item 16. The image resolution of the vacuum fluorescent indicating
tube is used as the standard image resolution and the setting value
of the other print heads are corrected variably.
With the structure described in Item 16, by using the image
resolution of the vacuum fluorescent indicating tube as the
standard image resolution, errors in the image resolution can be
refrained from occurring as far as possible and the image
resolution can be conformed with the target image resolution.
Item 17. When the image resolution of the print head is higher than
the standard image resolution, the data-element relationship
setting values are corrected so as to be enlarged in the aligning
direction of the recording elements, while when the image
resolution of the print head is lower than the standard image
resolution, the data-element relationship setting values are
corrected so as to be reduces in the aligning direction of the
recording elements.
With the structure described in Item 17, the image data is subject
to enlarging or reducing process so as to conform the image
resolution of the print head with that of the standard image
resolution without adding a new hardware.
Item 18. The data-element relationship setting values are corrected
by the number of pixels added into the image data for the
correction in the enlarging direction of the image data and by the
number of pixels eliminated from the image data for the correction
in the reducing direction of the image data. With the structure
described in Item 18, since the enlarging or reducing process for
the image data is conducted by adding or eliminating pixels, the
correction process for the image data can be conducted by a simple
calculation without adding a new hard ware.
Item 19. In the elimination of the pixels, the position of the
eliminated pixels are set to be different for each line of the
image data in the aligning direction of the recording elements.
With the structure described in Item 19, since an event that pixels
are eliminated at the same position can be avoided, the extent that
image pattern is lost can be minimized, thereby refraining image
quality from deteriorating.
Item 20. The data-element relationship setting value is an
enlarging ratio of image data for the correction in the enlarging
direction of the image data or a reducing ratio of image data for
the correction in the reducing direction of the image data.
With the structure described in Item 20, since the enlarging or
reducing process for the image data is conducted by adding or
eliminating pixels without adding a new hard ware such that pixel
correction is conducted with an even rate for the entire image
data, there is no influence due to addition or elimination of
pixels and image quality can be improved as far as possible.
Item 21. The standard image forming data are written on the memory
medium incorporated in the apparatus.
With the structure described in Item 21, the standard image can be
formed only by the present image recording apparatus.
Item 22. Means for measuring the standard image is incorporated in
the apparatus.
With the structure described in Item 22, the standard image is
measured only by the present image recording apparatus so as to
obtain the correction amount of the setting values, thereby
conducting correction for the setting values.
Item 23. The recording section and recording medium holding section
to hold a recording medium during recording are arranged so as to
be relatively shiftable in a direction different from the secondary
conveying direction.
With the structure described in Item 23, even when the image
recording medium is jammed and is unable to move relatively to the
recording section, restoration can be easily conducted, and
deviations in recording position caused by the restoration can be
easily rapidly corrected, whereby high quality image can be
provided stably.
Item 24. The print heads are arranged to be replaceable.
With the structure described in Item 24, when the print heads are
replaced due to deterioration, deviations in recording position can
be easily rapidly corrected, whereby high quality image can be
provided stably.
Item 25. The standard print head is a print head being unable to be
replaced.
With the structure described in Item 25, the setting values of only
the replaceable print heads may be adjusted based on the print head
being unable to be replaced.
Item 26. The plural pieces of print heads are integrated in a
single body.
With the structure described in Item 26, the print heads can be
shipped as a unit. Further, in the case that the print heads are
incorporated in the actual machine, deviations in recording
position caused by slight difference in relative moving speed
between the unit inspecting machine in the factory and the actual
machine due to wear on the conveying section can be easily rapidly
corrected, whereby high quality image can be provided stably.
Item 27. Correction for the data-element relationship setting
values are conducted based on a specific print head for only the
other print heads.
With the structure described in Item 27, since it is not necessary
to adjust the setting values and it is enough to adjust only the
other print heads, the adjustment time can be shortened
efficiently.
Item 28. Each print head conducts exposure recording with light
having different wavelength from others.
With the structure described in Item 28, in comparison with pixel
deviation reduction in the case of conducting the same color
exposure recording by plural print heads, great effect to reduce
color deviation can be obtained.
Item 29. The print heads comprises print heads for blue light
recording, green light recording and red light recording.
With the structure described in Item 29, color deviations in the
case that exposure recording is conducted with ordinary R, G, B
primary three colors can be reduced efficiently.
Item 30. The standard image is used to the image recording by at
least two pieces of print heads.
With the structure described in Item 30, the relative positional
relationship among print heads is clarified, whereby recording
deviations can be actually reduced. In particular, in color
recording, since different colors are indicated for each print
head, distinction becomes clear.
Item 31. All of the standard images necessary for the correction
are formed on a single sheet of the image recording medium.
With the structure described in Item 31, the recording position
deviations can be grasped at a glance.
Item 32. The standard images are formed in the smallest size
capable of being formed by the image recording apparatus.
With the structure described in Item 25, since an area used for
recording the standard image which is not used for an actual image
recording is made smallest, the loss of the image recording medium
can be minimized.
Item 33. The timing setting values includes a first timing setting
value to adjust a recording deviation between a print head and the
other print head and a second timing setting value to adjust the
recording position of an image on the recording medium and the
timing correcting means corrects the first timing setting value and
the second timing setting value based on the reference component
images.
Item 34. The arrangement setting values includes a first
arrangement setting value to adjust a recording deviation between a
print head and the other print head and a second arrangement
setting value to adjust the recording position of an image on the
recording medium and the arrangement correcting means corrects the
first arrangement setting value and the second arrangement setting
value based on the reference component images.
With the structure described in Items 33 and 34, In the case of
adjusting the recording deviation and the color deviation, in
particular, in the case of forming a no edge-frame print or a
borderless print which is popular in the photographic print, when
only the image recording position is to be adjusted in order to
avoid unnecessary white margin, the first timing setting value, the
second timing setting value, the first arrangement setting value
and the second arrangement setting value can be adjusted
independently, whereby the adjustment can be attained simply.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 a side view of a recording section of an image recording
apparatus.
FIG. 2 is a front view showing schematic structure of the recording
section in the image recording apparatus.
FIG. 3 shows a flow chart of exposure recording processing of image
data.
FIG. 4 is a drawing showing structure of a print head control
section.
FIG. 5 is a drawing explaining a method of correction between
pixels.
FIGS. 6(a) and 6b) are drawings explaining a measurement method of
absolute resolution.
FIG. 7 is a drawing explaining a method of pixel eliminating.
FIGS. 8(a)-8(c) are drawings explaining a correction method of
resolution by a bi-linear method.
FIGS. 9(a) and 9(b) are drawings explaining connection condition
between recording element blocks of print head.
FIG. 10 is a drawing explaining a method correcting resolution for
each of recording element block in the third embodiment.
FIG. 11 is a drawing explaining the occurrence of color blur and
color shift due to the difference of resolution.
FIG. 12 is a drawing explaining how to calculate an image signal at
an interpolated position by a linear interpolation method.
FIG. 13 is a drawing explaining how to calculate an image signal at
an interpolated position by a cubic-convolution method.
FIG. 14 is a block diagram showing a synchronous control circuit of
print head.
FIG. 15 is a timing chart showing operation of print head for G
colon.
FIG. 16 is a timing chart showing behavior of three color
synchronous control.
FIG. 17 is a timing chart showing behavior of three color
synchronous control.
FIG. 18 is a perspective view showing an example in which print
head of the same color is arranged in a zigzag form.
FIG. 19 is a drawing showing an arrangement of recording elements
in a zigzag form.
FIG. 20 is a time chart showing an example of how to set exposure
timing in the secondary scanning direction.
FIG. 21 is a drawing showing an example of a standard image for
adjusting exposure timing in the secondary scanning direction.
FIG. 22 is a drawing showing another example of a standard image
for adjusting exposure timing in the secondary scanning
direction.
FIG. 21 is a drawing showing still another example of a standard
image for adjusting exposure timing in the secondary scanning
direction.
FIG. 24 is a drawing showing an example of a standard image for
correcting pitch shift in the primary scanning direction.
FIG. 25 is a drawing for explaining mounting/removing condition of
unitized print head.
FIG. 26 is a perspective view showing another example of unitized
print head.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereinafter, embodiment of the present invention will be explained
referring to FIGS. 1 through 26.
First, FIGS. 1 and 2 show schematic structures of a recording
section of an image recording apparatus common to each embodiment.
FIG. 1 shows a side view of a recording section. FIG. 2 shows a
front view.
Color photographic paper 11 is conveyed in an arrowed direction in
FIG. 1 due to the rotation of supporting drum 13, while aforesaid
color photographic paper is supported by supporting drum 13 which
is actuated to be rotated by conveyance driving source 12 such as a
motor and pressure roller 14a. On the other hand, due to
controlling exposure section 15 in which print head 15R for R
(red), print head 15G for G (green) and print head 15B for B (blue)
in this order from the upstream side of aforesaid conveyance by
means of print head controlling section 16, image data inputted to
aforesaid print head controlling section 16 is exposed and recorded
on color photographic paper 11.
One example of aforesaid processing flow will be explained simply
using a flow chart exhibited in FIG. 3. First, to each of the
above-mentioned print head 15R, 15G and 15B, chart for resolution
measuring (described later) is outputted (Step 31, hereinafter
abbreviated as S31) so that resolution for each print head is
measured (S32). Here, measurement of resolution may be that of
absolute resolution or that of the difference of resolution for
each head.
Next, in order to coincide the resolution of each print head 15R,
15G and 15B, targeted resolution is set (S33), and then, a
conversion method of resolution for each print head (for each
color) is set (S34). Thus, after setting up resolution conversion
of an image recording apparatus, image data is inputted by means of
an ambient device such as a personal computer (S35). By the use of
a CPU of an image processing circuit in a recording apparatus,
resolution conversion processing is conducted (S36). An image is
outputted on color photographic paper 11 while there is no shift in
pixel position (S37). Incidentally, resolution conversion
processing may be conducted prior to S35 or in parallel with
S35.
Next, practical structure of exposure section 15 will be
explained.
In the present embodiment, print head 15R for R color employs an
LED print head in which the central wavelength of light emitting of
660 nm, resolution of 300 dpi and pixel number of 2560. Print heads
15G for G color and 15R for R color respectively employ vacuum
fluorescent print head (VFPH) which can separate colors easily by
means of color filters at relatively high illuminance end high
speed response.
A yellow filter and a blue filter are respectively added to the
beam path in print head 15G for G color and print head 15B for B
color so that Konica color QA paper type A6 (used as color
photographic paper 11, produced by Konica Corporation) is subjected
to color separation exposure. Incidentally, it goes without saying
that pixel numbers of print head 15G for G color and that of print
head 15R for R color and resolution of print head 15G for G color
and that of print head 15R for R color are respectively the same as
print head 15R for R colon However, since with regard to actual
resolution, as described above, error for print head may occur, the
present invention overcomes it.
Next, processing since image data is inputted to print head control
section 16 until it is exposed onto color photographic paper 11
will be explained.
FIG. 4 is a drawing showing practical structure of print head
control section 16. When image data having 2560 pixels in the
primary scanning direction and 3520 pixels in the conveyance
direction (secondary scanning direction) is recorded on color
photographic paper 11, image data for 2560.times.3520 pixels is
inputted into SCSI-II SCSI: Small Computer System Interface)
capable of communicating at high speed for each color from computer
41. From I/F 42, in addition to image data, correction values and
conversion coefficients such as sharpness conversion,
resolution-conversion, correction between pixels and gradation
conversion and data about print head interval are inputted into CPU
43. In this instance, image data is inputted from I/F 42, and the
following processing is conducted in succession.
Based on setting by CPU 43, as necessary, sharpness conversion
coefficient is sent to sharpness conversion section 44 from CPU 43
so that sharpness is converted. In aforesaid sharpness conversion,
sharpness of image is converted by stressing or flattening
contours, in which a 5.times.5 or 3.times.3 pixels convolution
filters are changed to be used on image data sent one by one for
each color.
Successively, in resolution conversion section 45, resolution of
image data after the sharpness is converted based on setting by CPU
43. Aforesaid image data is separated to each color gradient of R,
G and B by means of RGB date distribution section 46. Each color
gradient is stored in DRAM 47R, 47G and 47B.
Here, for simplifying explanation, processing of R color gradient
is exemplified to be explained. Among R gradient image data stored
in DRAM 47R, image data corresponding to one line in the primary
scanning direction is taken out of DRAM 47R and image data of
aforesaid one line is outputted to gradation conversion section
48R.
After the gradation of image data of aforesaid one line inputted to
aforesaid gradation conversion section 48R is converted based on
setting by CPU 43, aforesaid image data is inputted to correction
section 49R between pixels. In aforesaid conversion section 49R,
inputted image data is modified based on setting by CPU 43 in such
a manner that the inputted image data has the targeted gradation
properties.
In correction section 49R between pixels, correction between pixels
(described later) is conducted. An image outputting signal is
supplied to driver 50R which supplies an image outputting signal to
a print head, and color photographic paper 11, which is an image
recording medium, is exposed.
The above-mentioned processing is conducted to G gradient and B
gradient image data too in parallel, so that color photographic
paper is subjected to exposure. By photographic processing exposed
color photographic paper 11, visualized image of image data can be
obtained.
However, since, in FIG. 2, the mounting position of each of print
heads 15R, 15G and 15B cannot be coincided each other in the
secondary scanning direction, they are mounted with interval.
Namely, in FIG. 1, after a color photographic paper is exposed for
recording by means of print head 15R for R color and until
aforesaid color photographic paper 11 is exposed for recording by
print head 15G for G color, there exists conveyance time difference
which depends on conveyance speed and mounting interval in the
secondary scanning direction between print head 15R for R color
print head 15g for G color or pixel difference in the secondary
scanning direction. Accordingly, it is necessary to coincide pixels
recorded in color photographic paper 11 in the secondary scanning
direction.
Therefore, head interval in the secondary scanning direction
between print head 15R for R color and print head 15G for G color
and between print head 15G for G color and print head 15B for B
color were measured in advance. Based on aforesaid head intervals
measured, data "0" (actually, data which does not cause emitting
print head) is not caused to each recording pixel on print head 15G
for G color since print head 15R for R color starts exposure on
color photographic paper 11 until aforesaid exposure starting
position is conveyed to the exposure starting position of print
head 15G for G colon Due to this, the position of pixel in the
secondary scanning direction recorded onto color photographic paper
11 can be corrected.
In the same manner, the difference in the secondary scanning
direction of print head 15B for b color is corrected based on
interval with print head 15G for g color measured.
Incidentally, among image data of print head 15R for R color, for a
period after outputting the final primary scanning line until being
conveyed to the position of print head 15G for G color, it is
controlled that data "0" is continued to be outputted until
conveyance is finished without stopping outputting print head 15G
for G colon This is because that, in the case of after outputting
image data by print head 15G for G color, mechanism is more
simplified when each print head is synchronously operated. It is
not necessary for the print head in which data "0" is being sent to
operate during sending time. Driving may be stopped.
Next, correction between pixels is explained.
In the print head in which plural of the above-mentioned recording
elements are aligned linearly, there may be cases in which the
properties of emission amount on the inputted signal of each
recording element (pixel) are different. Specifically, when an
image is exposed for recording on a recording medium such as a
color photographic paper in which continuous gradation can tee
reproduced, density unevenness in accordance with the difference of
emission amount occurs on the recording medium due to aforesaid
property difference, causing image quality remarkably. In order to
unify property of emission amount of each recording element, it is
necessary to correct image data. Aforesaid correction processing is
correction between pixels.
Practically, as shown in FIG. 5, beam receiving sensor 52 is
provided on beam receiving side of print head 51 so that position
of beam receiving sensor 52 is shifted by sensor movement table 53
in such a manner that it becomes rightly below the recording
element which wants to measure beam by print head 51. Beam
receiving sensor 52 receives beam from each of recording element on
print head 51. The strength of irradiated beam is converted to
voltage by means of a photo-converter located inside for A/D
conversion, and then aforesaid strength is outputted to CPU 43.
When emission amount of each recording element is calculated as
described above, as properties of beam receiving sensor 52, it is
preferable that the property of outputted voltage on entering beam
amount has a linear relationship. Even when the voltage is
outputted un-linearly too, by measuring voltage properties on the
entering beam amount in advance, absolute beam amount can be
known.
In the present embodiment, as a beam receiving sensor, abeam
receiving sensor such as a photo-multiplier in which outputting on
entering beam amount has a linear relationship. In CPU 43, when a
voltage value is inputted from a beam receiving sensor, it is
divided by the standard voltage for forming a correction value
between pixels. Aforesaid correction value between pixels corrects
dispersion of beam emission amount of each recording element by
multiplying with image data when aforesaid image data is inputted
to each print head 15R, 15G and 15B. After preparing aforesaid
correction value between pixels, each print head is fixed against
supporting drum 13 as shown in FIG. 1.
Incidentally, supporting drum 13 is formed by a transparent
material. Inside aforesaid transparent supporting drum, a beam
receiving sensor is provided for measuring beam at an appropriate
frequency. Thereby, correction data may be prepared.
Next, a measurement method of resolution in the primary scanning
direction is explained.
It is preferable that resolution of each print head is ideally
targeted resolution. However, practically, since resolution is
different for each print head, the position of image recorded must
be aligned by processing images (magnifying/reducing image data in
the primary scanning direction).
Aforesaid magnifying/reducing processing includes addition/removal
processing of specific pixels, in addition to uniformly magnifying
initial image data.
The minimum requirements for setting resolution include that
resolution of each print head approximately relatively coincide. An
objective is attained by removing shift of pixel position.
The measurement method of resolution in terms of an absolute value
not of a relative value is, as shown in FIG. 6(a), is conducted
based on outputting results of a chart pattern in which 256 pixels
of blank is repeated to be inserted after recording one pixel. In
FIG. 6(a), recording is conducted every 256 pixels of intervals.
However, any intervals are allowed provided that a light emission
diode does not receive influence from light of a diode which emits
at the closest position (detection accuracy of the peak position
described later is improved). In addition, with regard to the
number of light emission diode, if several elements containing both
ends within an effective printing width are emitted for recording,
resolution measurement having favorable accuracy can be conducted
on print heads in which the position of each element is
intrinsically shifted.
Practically, with intervals as shown in FIG. 6(a), recording
signals for R color, G color and B color are transferred onto each
print head 15R, 15G and 15B for recording signals on a color
photographic paper. On a color photographic paper, cyan is colored
on R, magenta is colored on G and yellow is colored on B so that a
chart pattern for each color is formed.
The density value of aforesaid chart pattern is read for each color
with intervals thinner then pixel pitch by 5 times (for example, 5
.mu.m) in the primary scanning direction by the use of a
micro-densitometer, and then the central position of the peak of
the resulting density value (peak position) is calculated. FIG.
6(b) shows en example of the results. Here, in order to obtain
effective printing width w of print head, recording starting
position of the chart pattern is determined to be "address 0", and
recording finishing position is determined to be "address 2559".
Thereby, peak position 61 of the density value at "address 0" and
peak position 62 of the density value at "address 2559" are
determined. Between address 0 and address 2559 is defined to be
"effective printing width w". In order to obtain sufficient
accuracy, aforesaid effective numeral w is set in such a manner
that measurement error of w on the distance be 0.1% or less. The
effect of the present invention becomes prominent in a print head
whose w is 100 mm or more. Incidentally, if the chart pattern is
used only for calculating effective printing width w of the print
head, it is allowed that only lines are outputted at the positions
of addresses "0" and "2559" in FIG. 6(a).
From effective printing width w (mm), actual resolution D in the
primary scanning direction is calculated. Here, provided that
resolution D has dpi unit system, resolution D can be represented
by
Aforesaid resolution can be calculated for each of print head, and
used in an equation (5) described later.
Next, the first embodiment in which the difference of resolution at
both ends of the print head is measured and the image data is
corrected in order to minimize the difference between actual
resolution and targeted resolution, for example, nominal resolution
(300.0 dpi if in the case of a print head for 300 dpi
outputting).
As a method of correcting the difference between the actual
resolution and the targeted resolution, there is a method of
correcting apparent resolution of the print head by
magnifying/reducing image data in the primary scanning
direction.
Ordinarily, a bi-linear method, a linear interpolation method in
accordance with equation (2) described later and a
cubic-convolution method in accordance with equation (3). Algorithm
used in magnifying/reducing an image can be utilized as it is.
X.sub.1 =1+(u-[u])
X.sub.2 =u-[u]
X.sub.3 =1-(u-[u])
X.sub.4 =2-(u-[u])
f(t)=sin .pi.t/nt
In the case of linear interpolation, as shown in FIG. 12, image
signal Pat interpolation point u in equation (2) is a internal
separation point of image signals P.sub.1 and P.sub.2 of the front
and rear points x.sub.1 and x.sub.2. a.sub.1 represents length
between P and P.sub.1, and a.sub.2 represents length between P and
P.sub.2. In addition, in equation (3), image signal Pat
interpolation point u is calculated from, as shown by FIG. 13,
image signals P.sub.1, P.sub.2, P.sub.3 and P.sub.4 respectively at
addresses of x.sub.1, x.sub.2, x.sub.3 and x.sub.4. Here, x.sub.1,
X.sub.2, x.sub.3 and x.sub.4 represent integers. "u" represents a
real number. [u] is a rounded value of u.
Among above correction methods, a linear interpolation method and a
cubic-convolution method are excellent in terms of image. However,
a method using a bi-linear method is the simplest, in which
correction can be conducted without adding hardware newly.
Therefore, in the present embodiment, an example in which
correction was made using a bi-linear method.
Now, provided that the targeted resolution in the primary scanning
direction is 300.0 dpi, the corrected position when the bi-linear
method was used can be determined by the following equation.
Namely, as for targeted pixel width (in the present embodiment,
2560 pixels), from the difference of actual resolution D and
targeted resolution 300 dpi, pixel number N to be corrected is
calculated from equation (5) described later. From equation (6),
interpolation interval I in which at what interval
addition/elimination of pixels should be conducted is determined.
Here, "N" and "I" are integers. They are obtained by rounding the
right side values of equations (5) and (6). In the case of this
method, it is hypothesized that there is no shift of the pixel of
print head at the print head of address 0, the correction position
is set in such a manner that pixels are not either added or
eliminated at the position of address "0". In addition, in order
that the position of address 2559 finally meets, in other words,
interpolation is so set that each recording head coincides without
pixel shifting at both ends in the primary scanning direction when
an image is outputted at the maximum effective width, interpolation
is not conducted at such positions. Incidentally, when "N" value is
positive, pixels are added, end when N values is negative, pixels
are eliminated.
In this occasion, even when the number of pixels is the same, the
printing width of low resolution print head is longer and that of
high resolution become short. In such occasion, in order to the
printing width of high resolution print head, it is necessary to
reduce printing width of low resolution print head.
In aforesaid correction processing, if pixels are simply eliminated
at a certain position, the degree of extinguishing of image pattern
becomes prominent in a specific base, changing appearance of
image.
In such a case, it may be preferable that entire pixels on a line
in the primary scanning direction are divided into a block for
every I-th pixel so as to determine a pixel to be eliminated, that
a pixel is eliminated for every plural pixels, or that a pixel to
be eliminated is shifted for every line not so as to eliminate
pixels at the same position on the first line and on the subsequent
second line. That is, in the case that a pixel to be eliminated is
designated, a position of a pixel to be eliminated on the next
recording line is determined as a pixel other than the designated
pixel on the current recording line. As an example of a designating
method, a position of a pixel to be eliminated is determined on the
basis of random numbers generated by a random number generating
circuit, whereby errors caused by the eliminated pixels can be
dispersed onto the entire image.
FIG. 7 shows one example of aforesaid processing. In the status of
an image outputting signal onto a print head, following advancement
of recording of images, by shifting pixels to be eliminated one by
one regularly for recording, the degree of extinguishing of image
pattern can be lightened.
Incidentally, if a linear interpolation method or a cubic
convolution method is used, pixels are corrected equivalently all
through image data. Therefore, influence by image quality
deterioration due to elimination/addition of pixels is little.
Therefore, it is not necessary to add the above-mentioned method
specifically.
The above-mentioned image data correction is conducted in
resolution conversion section 45. However, if it is a simple
processing, correction may be conducted in the course of
transferring image from computer 41.
As explained above, in the present embodiment, by measuring
absolution value of the resolution of each print head by the use of
a chart pattern outputted by means of each print head, the
difference of resolution of each print head between actual
resolution and targeted resolution becomes apparent. Since
correction processing of image detain which image data is magnified
or reduced based on the difference of aforesaid resolution, shift
of pixel position due to the difference of aforesaid resolution can
be corrected accurately. Therefore, color shift of an image
recorded is minimized and color blur can be reduced.
Next, the second embodiment in which image data is corrected by
measuring shift amount of pixels of each print head at end portion
of print head in such a manner that resolution of each print head
should be met to that of the print head to be standardized.
FIG. 8(a) shows status of pixels of image outputting signal on two
print head before correction processing is conducted. Incidentally,
marks "0" represents a recording element of respective print head.
Numbers represents address of image outputting signal on DRAM. In
FIG. 8(a), when print headland print head 2 are coincided at a
position in accordance with address "0" (the left end portion of
the print head), the position of address 16 of print head 2 (the
right end portion of the print head) coincides the position of
address 17 of print head 1.
In such occasions, if "resolution" of the print head 2 is defined
to be the standard, position of image recorded can be coincided due
to magnifying processing of image data (image outputting signal) by
a bi-linear method. Namely, as shown in FIG. 8(b), by outputting
the pixel of address 7 which is located in the vicinity of the
center of the figure doubly, and then by outputting address 8 and
thereafter successively (not at the ambient section such as address
1 or address 15 from the viewpoint that the pixel position meets at
the ambient portion), one pixel is added to the image outputting
signal on print head 1 so that the position of address 15 on print
head 2 can be coincided with the position of address 15 on print
head 1.
If "resolution" of the print head 1 is defined to be the standard,
as shown in FIG. 8(c), resolution is corrected by outputting a
pixel on address 7 on the image outputting signal on print head
2.
Under the above-mentioned method, when the resolution of print head
15G for G color which is a color gradient having the highest visual
sensitivity is set to be the standard, deterioration of image
quality due to interpolation is inhibited and, thereafter,
recording is conducted after the position corresponding to address
0 of print head 15R for R color on DRAM is coincided with the
position of address "0" of print head 15G for G color, suppose that
the recording position of print head 15R for R color is shifted to
address "0" by about 500 .mu.m at the position of 2559th pixel of
print head. In this instance, by adding an image outputting signal
having a length corresponding to 500 .mu.m (for example, for 6
pixels [500/(25.4.times.1000/300)]=6) to an address in print head
15R for R color, resolution of each print head can easily be
met.
Incidentally, in the above-mentioned case, since B color gradient
is inferior from the viewpoint of both of visual sensitivity and
frequency properties, it is appropriate to increase interpolation
load.
Here, shift of recording position in the present embodiment
evaluates relative shift amount. Therefore, it is not necessary to
measure absolute resolution. Therefore, shift amount of the
recording position may compactly tee measured by the use of
magnifier roupe which can measure the length of chart pattern
outputted. Incidentally, in order to add/eliminate pixel of image
outputting signal, the same method as described in the first
embodiment may be adopted.
As explained above, in the present embodiment, due to that a print
head which would be the standard for resolution is set and
correction (magnification/reduction processing of an image
outputting signal) of resolution of the other print head is
conducted in such a manner that the resolution of the other print
head meets that of the standard print head, color shift is
compactly minimized and a visualized image in which color blur is
little can be obtained.
Next, the third embodiment in which image data is corrected by
measuring resolution for each of recording element block of the
print head.
For example, in the case that one print head is structured after
combining plural of recording element blocks each having 256 pixels
(recording element), connection error may occur for every recording
element block in addition to ordinary block pitch errors. Interval
of recording element at the connection section of the recording
element block are considered to be as shown in FIGS. 9(a) and
(b).
Namely, in FIG. 9(a), recording element block 91 and recording
element block 92 are separated from ordinary connection status. Due
to this, interval between pixel 93 and 94 is longer than the
interval of pixel inside each recording element block. On the other
hand, in FIG. 9(b), recording element block 95 and 96 are closer
than ordinary connection status, and therefor the interval of pixel
97 and 98 is shorter than pixel interval inside each block. This is
derived from that adjustment of adjoining pixel interval at the
joint section is difficult.
Since the above-mentioned connection status of the recording
element block is considered, it is difficult to hyposize that
pixels are located at a constant interval in the primary scanning
direction. Due to a method conducting a uniform image processing in
the primary scanning direction, it is impossible to prevent shift
of position of an image recorded. Since shift of resolution mainly
derives from combination error of recording element blocks, it is
desirable to divide pixels for each recording element block (for
example, 256 pixels) on the print head and to correct image data
after measuring resolution for each recording element block.
For example, if a recording element block is composed of 128
pixels, pixels are separated in the following manner that 0th to
127th pixels on the print head is defined to be the first recording
element block; 128th to 255th pixels are defined to be the second
recording element block. As shown in FIG. 6, line is outputted for
each of recording element block such as 0th pixel, 128th pixel,
etc., and a chart pattern is recorded. From this chart pattern,
resolution for each recording element block is measured.
Shift of resolution for each of the resulting recording element
block is corrected under the following procedure. For example, when
the resolution of print head 15G for G color is defined to be the
standard resolution, as shown in FIG. 10, first, the position of
0th pixel of print head 15G for G color is aligned with the
position of 0th pixel of print head 15R for R color. Then, pixel,
on print head 15R for R color, corresponding to the position of
127th pixel on print head 15G for G color is courted. If the
address of print head 15R for R color, on DRAM, which corresponds
to aforesaid pixel number is address 128, the pixel of image
outputting signal on the way is interpolated in such a manner that
aforesaid address 128 becomes 127. Incidentally, with regard to
pixel interpolation, methods described in the first embodiment and
the second embodiment can be used as they are.
As described above, on the position of 127th pixel on print head
15G for G color, address 127 is located on print head 15R for R
colon On the position of 128th pixel on print head 15G for G color,
address 128 is located on print head 15R for R colon.
Due to providing aforesaid processing successively on each
recording element block, it can be corrected that pixel recording
positions on print head 15R for R color and on print head 15G for G
color are located almost at the same position.
In addition, by providing similar correction processing on print
head 15B for B color, pixel recording positions on print head 15B
for B color and on print head 15G for G color are located almost et
the same position.
Incidentally, the print head which is the standard for resolution
is not necessarily print head 15G for G color.
As shown in the first embodiment, targeted resolution such as 300
dpi may be set, and then, image data on each print head may be
corrected in such a manner that each print head meets aforesaid
resolution.
In the case of the present embodiment, the difference at the joint
section of recording element block becomes in question, it is
effective to eliminate/add at the joins section of each recording
element block. However, there is no problem if correction is
conducted at the interim section inside each of recording element
block. The larger the size, the more the difference apparent.
When the linear interpolation method or the cubic convolution
method is used, line interval of the chart pattern may be aligned
to print head 15R for R color which is the standard of resolution.
Or, it may be set to meet the targeted resolution. Excess/shortage
of pixel may be corrected by means of the above-mentioned
method.
As explained above, in the present embodiment, on joint error for
each of recording element block having large possibility of the
occurrence on a print head such as an LED, the accuracy of the
position of an image recorded is increased to be aligned by
measuring resolution for each of recording element and correcting
image data in accordance with resolution for each of aforesaid
recording element block. Therefore, visualized image having higher
quality can be obtained.
Next, an embodiment in which position shift of exposure (recording)
between print heads in the secondary scanning direction is
corrected will be explained.
First, basic synchronous control of exposure timing of each print
head in the secondary scanning direction will be explained.
In FIG. 14, R color light source print head 230R is actuated by
means of operation clock CLK-R. G color light source print head
230G is actuated by means of operation clock CLK-G. B color light
source print head 230B is actuated by means of CLK-B.
R color light source print head control section 241R, G color light
source print head control section 241G, B color light source print
head control section 241B respectively generate operation clock
CLK-R, clock CLK-G end crock CLK-B. As described above, based on
respective clock, each print head is controlled and each image
corresponding to image data is recorded.
Timing of the above-mentioned operation of each print head control
section 241R, 241G and 241B for the recording of each of one line
is taken synchronous control by R timing signal S-R, G timing
signal S-G and B timing signal S-B respectively from synchronous
control section 242. FIG. 15 shows operation of G color, in which
when it receives G timing signal S-G from synchronous control
section 242, transfer of image bit data (MSB) for one line to G
color light source print head 230G is started. After a series of
the above-mentioned recording operation for one line for recording
operation time tg based on operation clock CLK-G, it becomes
stand-by status until it receives next timing signal S-G.
Incidentally, with regard to R color and B color, similar operation
is conducted. In control as shown in FIG. 15, light is emitted
during inable time which corresponds to the density value allotted
to each bit.
"t0" is a recording cycle of one line. Here, t0 is set to be 2.82
msec. as time in which exposure is conducted on photographic paper
P which is conveyed at an equivalent speed of 30 mm/see at the
pixel density of 300 dpi.
Synchronous control section 242 sends each timing signals S-R, S-G
and S-B for recording for one line at a cycle of "t0" for
conducting synchronous control of three colors for each of one
line.
FIG. 16 shows operation that synchronous control section 42 outputs
each timing signals S-R, S-G and S-B in such a manner that
recording starting position becomes for lines for each color on
photographic paper P become equivalent. However, the present
invention is not limited thereto. Control in which specific timing
in recording of one line becomes equivalent is allowed.
Specifically, by outputting each timing signal in such a manner
that the recording position at half of recording operation time of
each line for each color tr, tg and tb, i.e., tr/2, tg/2 and tb/2
on photographic paper P becomes equivalent, position of each color
dot of each line is more accurately superposed, thereby image of
high quality in which color shift is little is resulted in.
FIG. 17 shows an example in which outputting timing of each timing
signals S-R, S-G and S-B from synchronous control section 242 is
conducted teased on line finish signal S1. Line finish signal S1 is
a signal outputted to synchronous control section 242 from R color
light source print head control section 241R when one line
recording cycle (t0) of R color light source print head 230R is
finished. It is preferable since recording cycle (t0) of one cycle
can be adjusted simply only due to adjusting only one color while
synchronous control of each color for one line is kept and color
shift due to accumulation of shifting of frequency of recording
cycle for one line of each color is controlled, by charging
operation clock CLK-G, stand-by time Wr is changed or only
adjustment of R color light source print head control section 241R
is conducted.
If timing of each timing signal S-R, S-G and S-B are the same, it
is preferable if Si is sent to each print head control section
directly as S-R, S-G or S-B not through synchronous control section
242, because structure becomes simple.
In addition, by the use of conveyance position signal S2 sent from
conveyance control section 250 in place of S1 in FIG. 17, exposure
timing can be taken with a position at which photographic paper P
is conveyed. Therefore, even if there is conveyance speed
unevenness, the position of the image of each color can accurately
be controlled. There is a method to obtain conveyance position
signal S2 by detecting conveyance position of a photographic paper
by one line by one by detecting the rotation angle of the
conveyance roller by means of a rotary encoder.
Next, another example on the structure of the print head will be
explained hereinafter.
As shown in FIG. 18, in the exposure section for each color, plural
print heads of the same color having a length which is shorter than
the recording length for one line may be provided in a zigzag form
so that plural print heads has sufficient length for recording one
line.
In FIG. 18, R color exposure section 300R is structured by print
head 301R which uses LED arrays in which LED7R, which are recording
elements, are arranged in a line shape. With regard to LED array,
LED 7R may tee arranged approximately linearly. However, each LED
may be arranged in a zigzag form as shown in FIG. 19.
Here, set value of outputting timing of timing signals S-R, S-G and
S-B which determine exposure position of the above mentioned R, G
and B in the secondary scanning direction can relatively be
modified. FIG. 20 shows outputting status of the above-mentioned
timing signals S-R, S-G and S-B on a time series basis, in which
after receiving a conveyance position signal, exposure starting
signal Ra which is the first line of R, receiving (Pr)th pulse.
With regard to G and B too, the exposure starting signals G1 and B1
for the first line are sent, receiving (Pg)th and (Pb)th pulses
respectively. The values of the above-mentioned Pr, Pg and Pb are
at least relatively modifiable. In the present embodiment, the
pulse interval is set to recording cycle frequency t0 (=2.82 ms) of
the above-mentioned one line. Due to this, correction of image
shift one pixel unit in the secondary scanning direction. However,
pulse interval may not only be "t0". "t0/1", "0/3", "2t0" and "5t0"
may be allowed. Control can be conducted accordingly. For example,
if the pulse interval is "t0/2", color shift control on a
semi-pixel unit becomes possible.
The outputting frequency of the above-mentioned timing signals S-R,
S-G and S-B is not limited to taking synchronously by outputting
signals for one line as descried above. If color shift in the
secondary scanning direction is corrected as in the present
embodiment, it is considered not to be necessary to take
synchronously only if correction is conducted. Therefore, a type in
which the leading pixel outputs a signal every one image. If
synchronousity is taken every one line, the color shift control
function is more assured. However, control becomes too complicated
If synchronous control is conducted with every small number lines,
color shift due to piling of small amount of shift can sufficiently
be controlled.
It is possible to conduct exposure operation immediately after
receiving each timing signal. It is also possible to conduct
exposure operation after posing a certain time. By modifying set
amount for aforesaid certain time, more fine color shift control
compared with correction of the above-mentioned pulse frequency
unit can be conducted.
Next, formation of standard image for control color shift
inhibition in the above-mentioned secondary scanning direction will
be explained.
As in FIG. 21, aforesaid standard image is formed on an image
recording medium in accordance with standard image formation data
stored in a memory such as an ambient storage medium such as a
floppy disc, light magnetic disc and a memory card or a hard disc,
RAM and ROM inside the apparatus. In FIG. 21(1), with the standard
print head, for example specific print head, for example, exposure
timing of G color print head as the standard, an image is exposed
for recording while set amount of exposure timing of R color print
head is changed and shifted in the primary scanning direction in 13
steps from -6 to +6, and with G color print head a the standard, an
image is exposed for recording while set amount of B color print
head is changed are aligned.
In this occasion, in an example shown in FIG. 21, the amount
adjusted of R color print head is -1. That of B color print head is
+3. Respectively, standard G color print head and the exposure
recording position in the secondary scanning direction are
coincided.
FIG. 21(2) shows that, while exposure timing of R color print head
is defined to be the standard, the set value of the exposure timing
of exposure timing of G color print head and that of b color print
head is changed in 13 steps (from -6 to +6) aforesaid exposure
timing is shifted in the primary scanning direction for exposure
and recording.
In FIG. 21(2), the amount adjusted of G print head was -2, end the
amount adjusted of B print head as +3. Exposure recording position
of the standard R color print head in the secondary scanning
direction coincides.
Here, a shown in FIG. 21, all color are completely superposed in
terms of the length position of primary scanning direction of each
colon Apart of them may superpose, or nothing may superpose. All
type may be allowed. The situation is the same as in the standard
image for primary scanning direction descried later.
Based on measurement data by means of visual looking or scanner on
the standard image obtained as above, the set amount of exposure
timing is changed due to the numeral of the closest two pixels.
Provided that the initial vale was R of 100, G of 200 and B of 300,
In the case of the above-mentioned FIG. 21(1), if adjustment is
conducted in which r is -1, B is +3, the exposure recording
position coincides.
R=100-1=99
G=200 (the standard regular value)
B=300+3=303.
In the case of FIG. 21 (2), similarly,
R=100
G=200-2=198
B=300-3=297
As described above, after modifying the set value of the print head
of colors other than the standard color, the standard image may be
formed again and it is allowed that they are brought into closest
at .+-.0. It is similar in the case of the adjustment of color
shift in the primary scanning direction described later.
Incidentally, in the case of the standard image formed by the
present embodiment, set values of the print head of other colors
were adjusted with the print head of specific color as the
standard. Therefore, it is so preferable that adjustment can be
simplified. However, a structure in which the set value of the
print head of each color are independently adjusted. For example,
if the set value of each color is adjusted in such a manner that
the leading position of the color photographic paper (image
recording medium) conveyed as shown in FIG. 22 and the recording
starting position is aligned, recording can be conducted from the
leading end of a photographic paper without a margin.
This is also true in terms of the primary scanning direction.
If the set value is adjusted, in which it is determined from which
recording element image on the print head image data should be
recorded, it is possible to record the image to the right edge and
the left edge without any margin.
By the use of a similar chart as above, by adjusting the set value,
in which it is determined from which recording element on the print
head of the relevant color image data for each color should be
recorded, an image of high image quality in which color deviation
in the primary scanning direction is minimized can be obtained.
In the above-mentioned embodiment, when the linearity of the
arrangement of the recording element of each print head is
maintained, the amount of shifting of the recording position in the
secondary scanning direction is not changed depending upon the
position of the primary scanning direction. Therefore, if color
shifting is corrected et a specific one point in the primary
scanning direction, color shifting in other points can be
restricted.
However, strictly speaking, there is a production error. In
addition, the print heads are curved due to using environment and
secular change. In addition, the print head is amounted obliquely
on the secondary scanning direction. In addition, when paper
clogging occurred during operation, the recording section on which
the print head is loaded is moved for re-setting, the print head
may be set obliquely.
Therefore, embodiment in which adjustment of exposure timing is
independently conducted in accordance with the position of the
print head in the primary scanning direction.
According to Embodiment shown in FIG. 23, recording element row of
each print head is divided into plural of blocks 1, 2, 3 - - - so
that the exposure timing of each block in the secondary scanning
direction, i.e., recording position in the image recording medium
can be adjustable. Accordingly, with a specific print head (the
first head) as the standard, in each block, the print head (the
first head) records a prescribed length at an interval of 10 lines.
The second head records each line at an interval of 9 lines while
aforesaid each line is adjoined with the line of the
above-mentioned standard first head.
In the example of the standard image illustrated, in the second
head end the block 1, lines are superposed et .+-.0. Therefore,
with regard to aforesaid block 1, it is not necessary to modify the
set value of exposure timing. In the case of block 2, lines are
superposed at -1. Therefore, set value is decreased by 1.
Similarly, in the case of block 3, by reducing set value by 2, set
value can be adjusted for each block and recording position in the
secondary scanning direction can be coincided. With regard to the
remaining third head, based on a standard image similar to the
above, adjustment for each block can be conducted. In addition, at
the both sides of the recording of the standard first head,
recording of the second head end recording of the third head can
simultaneously be conducted. Recording area of the standard image
can be reduced.
Here, the above-mentioned standard first head may have the most
accurate linearity (when the kind of the head is different, it may
be selected from the viewpoint of the length and stiffness. In
addition, when a head is exchanged, it is preferable to select a
non-exchanged head). In addition, it is preferable to use the head
in which set amount between each block is adjusted between the end
of a photosensitive paper in advance.
In addition, division of the above-mentioned block can be conducted
appropriately. As described above, when one print head is formed by
joining plural heads, there is a possibility that position shift
occurs between each head. Therefore, it is rational to conduct
adjustment by dividing a block for each head.
Theoretically, it is possible to adjust each line by comparing
exposure timing for each of recording element with the standard
value. Though adjustment becomes too thin (the adjustment unit is
smaller than 1 pixel). If all recording elements are read by means
of a scanner at high accuracy and set amount is automatically
adjusted for each pixel, rapid and highly accurate adjustment can
be conducted.
Next, an embodiment in which recording position in the primary
scanning direction is adjusted (pitch shift is adjusted) will be
explained. An embodiment in which recording position adjustment in
aforesaid primary scanning direction was disclosed initially. Here,
as a standard image as the above-mentioned chars, a system in which
set value is easily corrected by recording recording position shift
in the primary scanning direction (pitch shift) in a state close to
actual condition will be shown.
In FIG. 24, after the exposure starting position for each of the
primary scanning direction line becomes identical between each
print head, while the pixel number of the standard print head is
kept equal with the number of recording element, to the print head
compared and adjusted, the pixel number for one line in the primary
scanning direction is added in the range of -3 to +3 (represented
by +), no modification or eliminated lines are recorded for a
prescribed length in the secondary scanning direction at the
starting position in the primary scanning direction, the central
position and the end position. Here, when i2, one pixel is added or
eliminated from the front portion and the trailing portion in the
primary scanning direction. When 35 3, one pixel is added or
eliminated from the front portion, the mid portion and the trailing
portion in the primary scanning direction for unifying.
For example, in the case of shown example in FIG. 24, +1 is
superposed on the standard line at the end position. Therefore, it
can be understood that, to the print head adjusted, an image data
in which one pixel is added is favorable.
Pixel number to be added or eliminated is known only looking at the
end position. However, if the interim position is recorded, it will
be referential when determining a position where a pixel is added
or eliminated. Specifically, in the case of three color print head
of R, G and B, by appropriately selecting the point of pixel added
or eliminated from comparing second or third print head, color
shift of three colors in the primary scanning direction can be
minimum not only at the end position but also at the middle
position. Note that the position where only pixel number added or
eliminated is read after recording only the end position and then
adding or eliminating may be calculated based on equation (6)
described above. In the case of three colors of R, G and B, in the
same manner as in adjustment in the secondary scanning direction
too, the standard color of the first head and the remaining 2
colors may be arranged one by one for recording. In addition,
recording area may be saved by recording the remaining 2 colors are
recorded at the right side and the left side of the standard color
simultaneously.
In the present embodiment, adjustment by magnifying or reducing
image data in which pixels were added or eliminated was shown. If
interpolation by means of each interpolation method such as a
linear interpolation method or a cubic-convolution is conducted,
recording position adjustment in the primary scanning direction may
be conducted by selecting magnification ratio or reduction ration
mostly closed to the line of the standard print head by conducting
line recording together with recording magnifying ratio and
reduction ratio (for example, .times.1.001 or .times.0.998) which
corresponds at a specific primary scanning position in the same
manner as in mentioned above by an image data magnified and reduced
by means of plural steps of magnification ration and reduction
ratio. In this occasion, pixel is corrected at a uniform ratio and
shift of recording position in the primary scanning direction can
be inhibited.
So far, embodiments on recording position adjustment in the primary
scanning direction described above and initially and recording
position adjustment in the secondary scanning direction were
explained. If they are structured singly, recording position shift
in the primary scanning direction and the recording position shift
in the secondary scanning direction can be inhibited. By combining
recording position shift in the primary scanning direction and the
recording position shift in the secondary scanning direction,
recording position shift in the primary scanning direction and in
the secondary scanning direction can be inhibited simultaneously,
truly high-quality image can be recorded.
If the present invention is applied to a monochrome image in which
an image is recorded with plural print head, shift of recording
position is minimized, and effects in which blur can be inhibited.
Specifically, when a color image is recorded employing print heads
for plural colors such as R, G and B, color shift can be inhibited.
Thereby, noticeable image quality improvement effects can be
obtained.
Next, mounting condition of plural print head onto an apparatus
main body will be explained.
It is better that aforesaid print head is mounted on the apparatus
main body removably. By this, if the print head is deteriorated, it
can be replaced. In this occasion, shift of recording position in
the primary scanning direction and the secondary scanning direction
which occur due to replacement can be inhibited by either of the
above-mentioned embodiments.
Here, if each print head can tee replaced independently, heads in
which deterioration is serious may only be replaced. Running cost
can be reduced. However, positional relationship with the other
print heads due to replacement may be shifted in multiple
direction. In addition, during operation, relative position shift
may occur between print heads. Therefore, adjustment becomes
complicated and frequency of adjustment has a possibility to be
increased.
Therefore, an embodiment, in which plural print head is integrally
mounted to form a unit end aforesaid unit maybe replaced, will be
shown.
FIG. 25(a) is a perspective view in which unit 39 is removed from
unit mounting section 38.
In unit mounting section 38, stand plate 38c is mounted on leg
section 38a and 38b. Between leg section 38a and 38b, photographic
paper P can be moved in an arrowed direction.
FIG. 25(b) is a plan view in which unit mounting section 38 was
viewed from above. On a portion shown by a dot line, unit 39 is
mounted. FIG. 25(c) is a perspective view of unit 39. Side surface
39a of unit 39 is pressed to an arrowed direction A with movable
member 38d. Side surface 39b of unit 39 is pressed to position
storing section 38e. Simultaneously, side surface 39c of unit 39 is
pressed with movable member 38f. By pressing side surface 39d of
unit 39 to position storing section 38g, unit 39 is fixed to unit
39 is removed from unit mounting section 38.
On the contrary, by moving movable members 38d and 38f to the
reversal direction of arrows A and B, cover is opened so that unit
39 can be taken out of unit mounting section 38.
Position storing sections 38e and 38g are movable respectively in
directions U and V, in which fine adjustment and moving mechanism
and fixing mechanism are provided. When unit 39 is mounted on unit
mounting section 38, by fine adjustment and moving mechanism of 38e
and 38g, it is adjusted in such as manner that unit 39 can be
mounted at a prescribed position. By fixing mechanism, unit storage
sections 38e and 38g, mounting position of unit 39 can be
stored.
Due to this, to mount unit 39 on the accurately same position as
unit 39 was previously removed. Therefore, maintenance property is
improved.
In this occasion, cables which connects each print heads 30R, 30G
and 30B and exposure control section 40 can easily be
removed/mounted from/to a connector.
FIG. 26 is an image recording apparatus in which photographic paper
P is conveyed plainly. Unit 60 is composed of two respectively
print heads 61 for R, G and B (totally, 6). One side along the
secondary scanning direction of print head mounting frame 62 of the
above-mentioned unit 39 is bound with a hinge. At the opposite
side, knob 63 is provided. By holding aforesaid knob 63, aforesaid
print head mounting frame 62 moves up and down perpendicular to
conveyance direction of conveyance direction for freely
openably/closely. In addition, aforesaid print head mounting frame
62 is set at a prescribed position controlled by a stopper through
spring 64.
Due to the above-mentioned structure, even if paper clogging occurs
as shown in FIG. 26, print head can be moved to a direction
different from conveyance direction as unit 60. Therefore,
photographic paper P can easily be removed. Thereafter, when unit
60 is re-set, even when color shift occurs, either of the each of
above-mentioned color shift is minimized for obtaining high image
quality image can be obtained.
* * * * *